docs(tls): add new dedicated page for TLS configuration

.github/actions/spelling/expect.txt

@@ -378,6 +378,7 @@ filecontents
 filterlist
 finalizable
 fingerprinter
+fipsmodule
 fizzaxbbuzz
 fizzbuzz
 fkn
@@ -797,6 +798,7 @@ opinsights
 oplog
 optimizable
 orgid
+OSSL
 ostype
 otel
 otelcol

Cargo.toml

@@ -349,6 +349,7 @@ nix = { version = "0.26.2", default-features = false, features = ["socket", "sig
 [build-dependencies]
 prost-build = { version = "0.12", default-features = false, optional = true }
 tonic-build = { version = "0.10", default-features = false, features = ["transport", "prost"], optional = true }
+# update 'openssl_version' in website/config.toml whenever <major.minor> version changes
 openssl-src = { version = "300", default-features = false, features = ["force-engine", "legacy"] }
 
 [dev-dependencies]

website/config.toml

@@ -33,6 +33,7 @@ undertagline = "Collect, transform, and route all your observability data with o
 subtagline = "Vector is deployed over 1,000,000 times per month by Fortune 500 companies and startups"
 alpine_js_version = "2.8.2"
 ionicons_version = "5.4.0"
+openssl_version = "3.1"
 site_logo = "img/vector-open-graph.png"
 display_banner = false # Whether to display the top banner in layouts/partials/banner.html
 favicon = "favicon.ico"

website/content/en/docs/reference/configuration/template-syntax.md

@@ -1,6 +1,6 @@
 ---
 title: Template syntax
-weight: 6
+weight: 7
 aliases: ["/docs/reference/templates", "/docs/reference/configuration/templates"]
 ---
 

website/content/en/docs/reference/configuration/tls.md

@@ -0,0 +1,150 @@
+---
+title: TLS configuration
+short: TLS configuration
+weight: 5
+aliases: [
+  "/docs/reference/tls",
+  "/docs/reference/configuration/tls",
+]
+---
+
+Vector implements cryptography and secure communication using the [OpenSSL][openssl] library.
+In particular, the official Vector binaries are statically linked against OpenSSL version
+{{< param openssl_version >}} and do not use any OpenSSL library installed on the running system.
+
+Note that OpenSSL recognizes a number of [environment variables][openssl-env] independently of Vector.
+
+## Trusted Certificates
+
+Trusted certificates (also called certificate authorities) are used for client and server verification.
+
+By default, OpenSSL and Vector will look for trusted certificates in the following locations:
+
+* A single file containing several certificates specified by the `SSL_CERT_FILE` environment variable.
+* A directory containing multiple certificate files specified by the `SSL_CERT_DIR` environment variable.
+* Probing of common default locations widely used by current operating systems.
+  * This probing functionality is provided to Vector by the [`openssl-probe`][openssl-probe] Rust crate.
+  * Trusted certificate location probing can be disabled by using the `--openssl-no-probe` command line
+    flag or the `VECTOR_OPENSSL_NO_PROBE` environment variable (refer to the [CLI][cli] documentation).
+
+Note that it is possible to use specific trusted certificates only for Vector via `SSL_CERT_FILE` or `SSL_CERT_DIR`.
+
+## OpenSSL Configuration
+
+The OpenSSL library in Vector can be configured using a [configuration file][openssl-config].
+
+By default, OpenSSL will look for a configuration file in the following locations:
+
+* A configuration file specified by the `OPENSSL_CONF` environment variable.
+* The predefined `/usr/local/ssl/openssl.cnf` configuration file.
+
+Note that it is possible to use specific OpenSSL configurations only for Vector via `OPENSSL_CONF`.
+
+## OpenSSL Implementation Providers
+
+In OpenSSL, a [provider][openssl-providers] is a code module that provides one or more implementations
+for various operations and algorithms used for cryptography and secure communication.
+
+OpenSSL provides a number of its own providers. The most important ones for Vector are:
+
+* The [default][openssl-providers-default] provider. This provider is built in as part of the _libcrypto_
+  library and contains all of the most commonly used modern and secure algorithm implementations.
+* The [legacy][openssl-providers-legacy] provider. This provider is a dynamically loadable module, and must
+  therefore be loaded and configured explicitly, using an [OpenSSL configuration](#openssl-configuration).
+  It contains algorithm implementations that are considered insecure, or are no longer in common use such as MD2 or RC4.
+* The [FIPS][openssl-providers-fips] provider. This provider is a dynamically loadable module, and must
+  therefore be loaded and configured explicitly, using an [OpenSSL configuration](#openssl-configuration).
+  It contains algorithm implementations that have been validated according to the [FIPS 140-2][fips-140-2] standard.
+
+By default, the OpenSSL library in Vector uses the _default_ provider which includes modern and secure
+algorithm implementations. If necessary, the _legacy_ provider can be used instead for deployments where
+older and more insecure algorithms are still in use.
+
+### Legacy Provider Example
+
+To use the _legacy_ provider in Vector, first create an OpenSSL configuration file as follows:
+```ini
+openssl_conf = openssl_init
+
+[openssl_init]
+providers = provider_sect
+
+[provider_sect]
+default = default_sect
+legacy = legacy_sect
+
+[default_sect]
+activate = 1
+
+[legacy_sect]
+activate = 1
+```
+
+Then, run Vector with `OPENSSL_CONF` set to the path where the file above can be found:
+```sh
+OPENSSL_CONF=/path/to/openssl-legacy.cnf \
+    vector --config /path/to/vector.yaml
+```
+
+Note that if the above configuration file is saved in `/usr/local/ssl/openssl.cnf` Vector will automatically
+find it without using `OPENSSL_CONF`. However, this approach is not recommended because other applications
+in the running system may also use this file and unintentionally switch to the legacy provider.
+
+### FIPS Provider Example
+
+To use the _FIPS_ provider in Vector, the [OpenSSL FIPS module][openssl-fips-module] must be installed
+and [configured][openssl-fips-module]. This is beyond the scope of this document, however
+[instructions][openssl-fips] can be found in the OpenSSL repository.
+
+Not all versions of the OpenSSL FIPS module have been validated. However, it is possible to use previous
+validated versions of the FIPS module with newer versions of OpenSSL, such as the version used in Vector.
+This use case is also documented in the installation instructions linked above.
+
+Once the FIPS module is installed and configured, a `fips.so` (on Unix) or `fips.dll` (on Windows)
+module file, and a `fipsmodule.cnf` configuration file should be available to use in Vector.
+
+An OpenSSL configuration file must be then created as follows:
+```ini
+config_diagnostics = 1
+openssl_conf = openssl_init
+
+.include /path/to/fipsmodule.cnf
+
+[openssl_init]
+providers = provider_sect
+alg_section = algorithm_sect
+
+[provider_sect]
+fips = fips_sect
+base = base_sect
+
+[base_sect]
+activate = 1
+
+[algorithm_sect]
+default_properties = fips=yes
+```
+
+Then, run Vector with `OPENSSL_CONF` set to the path where the file above can be found and
+`OPENSSL_MODULES` set to the path where the FIPS module files are installed:
+```sh
+OPENSSL_CONF=/path/to/openssl-fips.cnf \
+OPENSSL_MODULES=/path/to/fips-modules \
+    vector --config /path/to/vector.yaml
+```
+
+Note that if the running system already has a system-wide OpenSSL FIPS installation and an OpenSSL
+configuration file for it, Vector can also use them directly via the above environment variables.
+
+[cli]: /docs/reference/cli
+[fips-140-2]: https://en.wikipedia.org/wiki/FIPS_140-2
+[openssl]: https://www.openssl.org/
+[openssl-config]: https://www.openssl.org/docs/man{{< param openssl_version >}}/man5/config.html
+[openssl-env]: https://www.openssl.org/docs/man{{< param openssl_version >}}/man7/openssl-env.html
+[openssl-fips]: https://github.com/openssl/openssl/blob/master/README-FIPS.md
+[openssl-fips-module]: https://www.openssl.org/docs/man{{< param openssl_version >}}/man7/fips_module.html
+[openssl-probe]: https://github.com/alexcrichton/openssl-probe
+[openssl-providers]: https://www.openssl.org/docs/man{{< param openssl_version >}}/man7/provider.html
+[openssl-providers-default]: https://www.openssl.org/docs/man{{< param openssl_version >}}/man7/OSSL_PROVIDER-default.html
+[openssl-providers-fips]: https://www.openssl.org/docs/man{{< param openssl_version >}}/man7/OSSL_PROVIDER-FIPS.html
+[openssl-providers-legacy]: https://www.openssl.org/docs/man{{< param openssl_version >}}/man7/OSSL_PROVIDER-legacy.html

website/content/en/docs/reference/configuration/unit-tests.md

@@ -1,7 +1,7 @@
 ---
 title: Unit testing Vector configurations
 short: Unit tests
-weight: 5
+weight: 6
 aliases: [
   "/docs/reference/tests",
   "/docs/reference/configuration/tests",

website/content/en/docs/setup/going-to-prod/hardening.md

@@ -53,7 +53,7 @@ Vector implements an affine type system via Rust that achieves memory safety and
 
 #### Securing Vector’s Artifacts
 
-- **Download over encrypted channels.** Vector does not allow unencrypted downloads of its artifacts. All download channels require industry-standard TLS for all connections. When downloading Vector be sure to enable SSL verification (the default for most clients).
+- **Download over encrypted channels.** Vector does not allow unencrypted downloads of its artifacts. All download channels require industry-standard TLS for all connections. When downloading Vector be sure to enable server certificate verification (the default for most clients).
 
 #### Securing Vector’s Configuration